001.SSM之MyBatis

项目构成：

1. 配置文件
2. 实体类
3. 映射文件
4. 测试类
5. 接口文件
6. 依赖包

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配置文件

• 配置类的别名
• 数据库连接配置

• 关联映射文件

  config.xml

  <?xml version="1.0" encoding="UTF-8"?><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><typeAliases>    <!-- type就是完整实体类名， -->    <typeAlias type="com.wsk.test.User" alias="User"/></typeAliases><environments default="development">    <environment id="development">        <transactionManager type="JDBC" />        <!-- 数据库连接配置 -->        <dataSource type="POOLED">            <property name="driver" value="com.mysql.jdbc.Driver" />            <property name="url" value="jdbc:mysql://localhost:3306/db_ke" />            <property name="username" value="root" />            <property name="password" value="123456" />        </dataSource>    </environment></environments><mappers>    <!-- 关联映射文件 -->    <mapper resource="com/wsk/test/UserMapper.xml"/></mappers></configuration>

实体类

• javabean

  User.java

  package com.wsk.test;public class User {int id;String username;public int getId() {    return id;}public void setId(int id) {    this.id = id;}public String getUsername() {    return username;}public void setUsername(String username) {    this.username = username;}public String toString(){    return id+"--"+username;}}

映射文件

• 实体类和表映射

• 数据库操作

  UserMapper.xml

  <?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!-- 指定唯一的namespace，惯例是包名+文件名--><mapper namespace="com.wsk.test.UserMapper"><!-- 类与表映射配置 --><resultMap id="user_table"  type="User">    <id property="id" column="id"/>    <result property="username" column="name"/></resultMap><!-- 查询操作 --><select id="getUser" parameterType="int"     resultMap="user_table">    select * from user where id=#{id}</select><!-- 创建表--><update id="createUserTable">    create table user(        id int(6),        name varchar(10),        primary key (id)    )</update></mapper>

测试类

• 先在数据库中创建user表和相应数据

  Test1.java

  package com.wsk.test;import java.io.IOException;import java.io.InputStream;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class Test1 { public static void main(String[] args) throws IOException {     //使用类加载器加载mybatis的配置文件（同时加载关联的映射文件）      InputStream is = Test1.class.getClassLoader().getResourceAsStream("conf.xml");     //构建sqlSession的工厂     SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);     //创建能执行映射文件中sql的sqlSession     SqlSession session = sessionFactory.openSession();      // session.update("com.wsk.bean.UserMapper.createUserTable");      String statement = "com.wsk.test.UserMapper.getUser";//映射sql的标识字符串      //执行查询返回一个唯一user对象的sql      User user = session.selectOne(statement, 11);     System.out.println(user.toString());    }}

接口文件

• 与映射文件名一致

  UserMapper.java

  package com.wsk.test;public interface UserMapper {    public User getUser(int id);}

  测试类

  package com.wsk.test;import java.io.IOException;import java.io.InputStream;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class Test1 {    public static void main(String[] args) throws IOException {        //使用类加载器加载mybatis的配置文件（同时加载关联的映射文件）        InputStream is = Test1.class.getClassLoader().getResourceAsStream("conf.xml");        //构建sqlSession的工厂        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);        //创建能执行映射文件中sql的sqlSession        SqlSession session = sessionFactory.openSession();        UserMapper mapper=session.getMapper(UserMapper.class);                    User user=mapper.getUser(11);        System.out.println(user.toString());    }}

依赖包

• mybatis-3.2.8.jar
• mysql-connector-java-5.1.29.jar
• demo